Principal English Translation:
to have someone keep something, to lend something to someone
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 229.
Alonso de Molina:
pialtia. nitetla. (pret. onitetlapialti.) depositar o dar aguardar algo a otro.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 81v. col. 1. Thanks to Joe Campbell for providing the transcription.
pialtia. ninote. (pret. oninotepialti.) encomendarme a otro, o fiar mi persona del que pienso que me aprouechara.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 81v. col. 1. Thanks to Joe Campbell for providing the transcription.
Lockhart’s Nahuatl as Written:
nic. Class 3: ōnicpialtih. causative of pia. 229
Attestations from sources in English:
At concujzque, at conanazque, at conmopialtizque = Perhaps they will grasp it, take it, hold fast to it (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 83.
Attestations from sources in Spanish:
yn noteoyotica nopiltzin ton Pelolo te la Clox moetztica ypan tlaxilacali Xata Calala ypanpa ca yehuatl onicpielti yn cequi amatl = a mi ahijado don Pedro de la Cruz, que vive en el barrio de Santa Clara, para que solicite los papeles que le di a guardar (Zempoala, "1610", but probably Techialoyan -related)
Vidas y bienes olvidados: Testamentos en náhuatl y castellano del siglo XVII, vol. 3, Teresa Rojas Rabiela, et al, eds. (México: CIESAS, 2002), 96–97.